Mr Hague said rape was one of the "great mass crimes" of modern times.

He called on the more than 140 nations at the summit to write action against sexual violence into their army training.

The summit aims to:

launch a new international protocol for documenting and investigating sexual violence in conflict, and encourage countries to strengthen domestic laws to enable prosecutions

urge countries to train all soldiers and peacekeepers to prevent sexual violence

increase funding to support survivors of sexual violence

change attitudes towards rape in conflict

The organisers want the event to be the moment the world wakes up and declares that sexual violence is not an inevitable part of war, says BBC World Affairs Correspondent Paul Adams.

'Weapon of war"

Opening the summit, Mr Hague said: "From the abolition of slavery to the adoption of the Arms Trade Treaty, we have shown that the international community can tackle vast global problems in a way that was once considered to be impossible.

"There is power in numbers, and if we unite behind this cause, we can create an unstoppable momentum and consign this vile abuse to history."

Ms Jolie said: "We need to shatter that culture of impunity and make justice the norm, not the exception, for these crimes."

She said she wanted to dedicate the conference to a rape victim she recently interviewed in Bosnia, who felt so humiliated by what had happened to her that she could not even tell her own son.

"She felt that having had no justice for her particular crime, in her particular situation, and having seen the actual man who raped her on the streets free, she really felt abandoned by the world,'' Ms Jolie said. "This day is for her.''

Mr Hague has visited several war zones with Ms Jolie to meet victims of sexual violence in recent years

Angela Atim, one of the speakers at the conference, was kidnapped as a 14-year-old schoolgirl by Lord's Resistance Army (LRA) rebels in Uganda.

She told the BBC: "These people who are accountable for the sexual violence in armed conflict, they have to be brought to justice."

"It's part of our healing because it's really painful to see that they are still walking around, they are still doing the same thing."

Nations taking part in the summit include Bosnia, the Democratic Republic of Congo and Somalia - countries where sexual violence has happened "on a vast scale", Mr Hague told the BBC.

Sexual violence was systematically being used as a weapon of war in the 20th and 21st Centuries, he noted.

Mr Hague cited the estimated 50,000 women who were raped in Bosnia two decades ago, virtually none of whom have received justice.